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authorAndy Lutomirski <luto@kernel.org>2016-04-26 08:52:44 -0700
committerIngo Molnar <mingo@kernel.org>2016-04-26 19:52:57 +0200
commite16d8a6cbb499c5c8bfe9330d3351b649bded4af (patch)
tree16f6883c63a4930e717bb4078dc385fb7a75bcd9 /arch
parent707e59ba494372a90d245f18b0c78982caa88e48 (diff)
Revert "x86/mm/32: Set NX in __supported_pte_mask before enabling paging"
This reverts commit 320d25b6a05f8b73c23fc21025d2906ecdd2d4fc. This change was problematic for a couple of reasons: 1. It missed a some entry points (Xen things and 64-bit native). 2. The entry it changed can be executed more than once. This isn't really a problem, but it conflated per-cpu state setup and global state setup. 3. It broke 64-bit non-NX. 64-bit non-NX worked the other way around from 32-bit -- __supported_pte_mask had NX set initially and was *cleared* in x86_configure_nx. With the patch applied, it never got cleared. Reported-and-tested-by: Meelis Roos <mroos@linux.ee> Signed-off-by: Andy Lutomirski <luto@kernel.org> Cc: Andy Lutomirski <luto@amacapital.net> Cc: Borislav Petkov <bp@alien8.de> Cc: Brian Gerst <brgerst@gmail.com> Cc: Denys Vlasenko <dvlasenk@redhat.com> Cc: H. Peter Anvin <hpa@zytor.com> Cc: Linus Torvalds <torvalds@linux-foundation.org> Cc: Mike Galbraith <efault@gmx.de> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Thomas Gleixner <tglx@linutronix.de> Link: http://lkml.kernel.org/r/59bd15f7f4b56b633a611b7f70876c6d2ad01a98.1461685884.git.luto@kernel.org Signed-off-by: Ingo Molnar <mingo@kernel.org>
Diffstat (limited to 'arch')
-rw-r--r--arch/x86/kernel/head_32.S6
-rw-r--r--arch/x86/mm/setup_nx.c5
2 files changed, 3 insertions, 8 deletions
diff --git a/arch/x86/kernel/head_32.S b/arch/x86/kernel/head_32.S
index 54cdbd2003fe..af1112980dd4 100644
--- a/arch/x86/kernel/head_32.S
+++ b/arch/x86/kernel/head_32.S
@@ -389,12 +389,6 @@ default_entry:
/* Make changes effective */
wrmsr
- /*
- * And make sure that all the mappings we set up have NX set from
- * the beginning.
- */
- orl $(1 << (_PAGE_BIT_NX - 32)), pa(__supported_pte_mask + 4)
-
enable_paging:
/*
diff --git a/arch/x86/mm/setup_nx.c b/arch/x86/mm/setup_nx.c
index 8bea84724a7d..f65a33f505b6 100644
--- a/arch/x86/mm/setup_nx.c
+++ b/arch/x86/mm/setup_nx.c
@@ -32,8 +32,9 @@ early_param("noexec", noexec_setup);
void x86_configure_nx(void)
{
- /* If disable_nx is set, clear NX on all new mappings going forward. */
- if (disable_nx)
+ if (boot_cpu_has(X86_FEATURE_NX) && !disable_nx)
+ __supported_pte_mask |= _PAGE_NX;
+ else
__supported_pte_mask &= ~_PAGE_NX;
}